Moss

By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester

Tryon Creek State Natural Area (TCSNA) is the home to pileated woodpeckers, garter snakes and much more. On any given day you may or may not see a pileated woodpecker or a garter snake, but you will see moss.  There are a number of different species of moss that grow in TCSNA.  Many are commonly found growing on both living and dead tree trunks.    

What is Moss?

Moss is a plant that is radically different than most of the other plants in the forest. In botanical terms it is in the same kingdom as other plants (Plantae), but that’s where the likeness stops. Moss is in the phylum (aka Division) Bryophyta, ferns and horsetails are in the phylum Pteridophyta, Douglas-firs are in the phylum Coniferophyta, and bigleaf maples are in the phylum Magnoliophyta. This means that moss is as closely related to Douglas-fir and bigleaf maple as humans are to spiders!

Spider
Human

— Photos by Bruce Rottink

What Does Moss Do?

The moss is not hurting the tree.  It is only living on the tree because growing on the tree trunk has several advantages for the moss.  First, the moss is high up in the air (think: “closer to the sun”) without having to expend any energy to grow a big stem.  Secondly, in those trees with upward angled branches, the rain water falling on the tree will be directed down the trunk where it can be absorbed by the moss.  Thirdly, the rainwater flowing down the trunk can be higher in nutrients because the rain water can dissolve those nutrients from the tree’s leaves and branches.  In red alder, scientists discovered that the water flowing down the trunk contained 11 times as much nitrogen as regular rainwater. 

photo by Bruce Rottink
Upward Angled Branches on a Red Alder

The mosses growing on the sides of tree trunks can be incredibly thick.  A very tall alder tree growing alongside the Middle Creek trail was cut down because it was a hazard to hikers.  I examined the moss growing on that tree, and found it was about 4 inches thick, as seen in the photo below.

photo by Bruce Rottink
Moss on a tree stem at Tryon Creek SNA

The bottom layers of moss are dead and brown, but the moss on the surface is alive and green.  I collected all the moss that was growing on a 12” X 12” section of the tree trunk.  I took this sample home and soaked it in water.  I then laid the sample on a screen, and left it there until water stopped dripping out of the moss.  I weighed the wet moss, and then dried it out and weighed it.  Based on this experiment, and my measurements of the main tree trunk, I estimated that if the entire trunk were covered with a layer of moss this thick, and all of the layers were soaked, it could hold up to 1500 lbs. of water.

While “exploring” the moss from the alder tree, I discovered both spiders and slugs living in the moss.  Doubtless a safe and comfortable place to live.

photo by Bruce Rottink
This slug was found in moss growing on the side of a tree at Tryon Creek SNA.

How Fast Does Moss Grow?

Sometimes bad things can create interesting opportunities.  One day while walking on the Cedar Trail, I encountered a man pulling the moss off a bigleaf maple tree.  He said he thought the moss was hurting the tree (not true!)  However, his actions created a great opportunity to study the recovery process of the moss.  This is illustrated in the pictures that follow.

                                               

        — Photo by Bruce Rottink
Bigleaf maple tree on Cedar Trail on Sept. 23, 2016 shortly after all the moss was stripped off the lower trunk. 

                                              

     — Photo by Bruce Rottink
Bigleaf maple tree trunk exactly 16 months after all moss was stripped off.

                                                             

   — Photo by Bruce Rottink
Close up of new moss growing 16 months after all moss was stripped off this bigleaf maple tree trunk.  (Ruler is in inches.)

                 

– photos by Bruce Rottink
Bigleaf maple tree trunk 2 years and 4 months (January 2019) after all moss was stripped off the lower trunk.  Inset is close-up of my thumb, and the middle section of the trunk.

                                                                           

           —- Photo by Bruce Rottink
Moss growing 3 years and 6 months after all the moss was stripped off this bigleaf maple tree’s trunk.

                                                                                  

      —- Photo by Bruce Rottink
Close up of moss growing 3 years and 6 months after all the moss was stripped off this bigleaf maple tree’s trunk.

It is obvious that the moss is starting to recover, but it is also clear that it will take a long time for the moss on the tree to get back to “normal”.  The undisturbed areas of moss growing above the section where it was pulled off is currently just over 2 inches thick.  

Spreading the Moss

Moss spreads by means of spores.  These spores are produced by sporangia, stalks with a capsule full of spores at the end.  The sporangia in the photo below have not quite ripened, but soon will open and the spores inside will disperse to other sites.  At Tryon Creek over the years I’ve recorded seeing sporangia from November through February.  Some spores may doubtless be produced outside this timeframe.

                                                                             

               —- Photo by Bruce Rottink
Moss sporangia growing on the side of a tree at TCSNA.

Diversity in the Forest

The forest at Tryon Creek SNA is not just one uniform environment, but dozens and dozens of micro-environments that provide homes to a huge diversity of both plants and animals.  It was a good move to preserve this natural environment so we all could keep learning about life on our planet. 

A Lichen Awakes

By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester

A lichen is actually a combination of an algae, a fungus, and sometimes a yeast.  The algae use sunlight to photosynthesize which produces the “food” that keeps everything alive.  The lichens at Tryon Creek State Natural Area (TCSNA) are extremely varied in their forms, as was pointed out in an earlier Naturalist Note (https://tryoncreek.wordpress.com/tag/lichen/).

Some lichens grow low down on the trunks of trees or on rocks, and others grow high up in the tree crowns.  The plus side of growing in the crown is that they get good exposure to the sunlight without having to expend the energy required to grow a large trunk like a tree.  The down side is that with no roots, they sometimes, especially in the summer, are left “high and dry.”  Not a good thing!

Fortunately, lichens very rapidly respond to available water, like when it rains in the tops of trees, the lichens change from looking all wilted and curled to a more expanded version quite quickly.

To demonstrate this, I collected a dead branch with some lichens growing on it.  I let the branch dry out for more than a week.  The lichens looked a bit curled and shriveled after they were dry.  Then on a nice sunny day I laid the branch out on my picnic table, and took a movie while I sprayed it with water.  The lichen changed dramatically in a matter of a minute.

Watch the movie here:  https://www.facebook.com/FriendsofTryonCreek/videos/876165402849649/

As you watch, you will note that there are some significant changes in form.  I particularly recommend watching the lichen on the upper left part of the branch.  To begin, double click on the icon below.  After watching this once in “real time”, put your computer’s pointer on the circle at the bottom of the picture, and pull it swiftly across the timeline at the bottom of the picture.

Sometimes the changes in nature are slow, but sometimes they are very fast.  These lichens, having chosen to live in a somewhat harsh environment, have survived by reacting quickly when the much needed water becomes available.

 

Ferns: The Other Half of the Story

By Bruce Rottink, Volunteer Nature Guide & Retired Research Forester

All photos by Bruce Rottink.

 

If you’ve ever been to Tryon Creek State Natural Area (TCSNA) you’ve probably seen lots of ferns, and know what ferns look like.  Or do you?  Many people don’t realize that ferns go through two vastly different life stages, and what we typically think of as “ferns” represent only one of those two stages.

The predominant stage of two of the many fern species that are fairly common at the park are pictured below.  These ferns are oftentimes more than a foot and a half tall.  These are the part of the ferns’ life cycle that we are familiar with.

 

photo 1

Maindenhair fern at Tryon Creek State Natural Area.

 

photo 2

Sword fern at Tryon Creek State Natural Area.

 

These ferns are diploids, meaning they have two sets of genes, one from each parent, just like you and I do in our body.  This stage in the life of a fern is called the sporophyte stage because this is the stage that produces spores.  Below are pictures of the spore cases (technical name is “sporangia”) found on at least some of the leaves of most ferns.

 

photo 3

Spore cases on the underside of a sword fern leaf at Tryon Creek State Natural Area.

 

photo 4

Spore cases on the edge of maidenhair fern leaves at Tryon Creek State Natural Area.

 

photo 5

Closeup of a mature maidenhair fern spore case. Note the yellow spores on the leaf and inside case.

 

I was interested in seeing the other, smaller stage of the fern life cycle.  I collected some spore-bearing fronds from a sword fern.  I put them on a sheet of paper to dry out and release the spores from the spore cases.  The picture below shows the pile of empty spore cases, and the pile of spores that were released.

 

photo 6

Left: Empty sword fern spore cases. Right: sword fern spores. The spores are so tiny, they look like an out-of-focus dust pile.

 

These spores are haploid, meaning they only have one set of genes.  In that way, they are comparable to the sperm and ova (eggs) of human beings.  These spores are released by the fern and spread around in the breeze to new places.  A tiny fraction of these spores will land in suitable places to “germinate.”

 

I put the spores in some plastic boxes half-filled with soil, watered them, and monitored their development.  All of these boxes were kept on a table in my home office under a lamp that provided at least 14 hours of light every day.

 

When the spores germinate they produce little haploid “plants” (called gametophytes) that start to grow.  These gametophytes produce both the eggs and sperm of the fern.  However, to encourage cross-breeding, the sperm and eggs on any given gametophyte will mature at different times.  This timing difference forces cross pollination.  Different stages of the gametophytes are seen in sequence of photos below.

 

photo 7

Very young sword fern gametophyte.

 

photo 8

More developed sword fern gametophyte.

 

photo 9

Mature sword fern gametophyte. Yellow arrow points to the hair-like rhizoids, which function like the roots of regular plants. The red arrow points to the main body of the gametophyte.

 

This sword fern gametophyte will produce both eggs, in the archegonia (singular = archegonium), and sperm in the antheridia (singular = antheridium).  Each gametophyte will produce eggs and sperm at different times, so the sperm from one will have to swim to an archegonium on another gametophyte to fertilize it.  After the eggs are fertilized, they will develop into a “normal looking” fern.  After fertilization they return to their diploid (2 sets of genes, just like you and me) phase which is the sporophyte phase that we are familiar with.  A very young diploid sword fern is shown in the picture below.  Note that in this very young phase their leaves look much different than the leaves on a mature sword fern.

 

photo 10

Young sporophyte stage sword fern.

 

The life cycle of the fern is different from most of the plants in our forest, but when you start to think about how many ferns there are at Tryon Creek State Natural Area, it’s pretty clear that this form of reproduction has served the ferns well.

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